Cooling device for electrical or electronic components having a base plate and cooling elements and method for manufacturing the same

ABSTRACT

In order to improve the function and to simplify the manufacture of a cooling device for electrical or electronic components, rib-like cooling elements are positioned parallel and at a predetermined distance from one another and are connected to a base plate in heat-transmitting contact. At least two cooling elements are combined into a unitary ribbon-shaped package having a U-shaped profile in cross-section and a web portion which connects the cooling elements. The cooling elements being fixed to the base plate in corresponding longitudinal slots.

This is a divisional of applications U.S. patent, application No.08/769,547 filed on Dec. 19, 1996, now U.S. Pat. No. 5,791,406 and U.S.Provisional Application No. 60/008,932 filed on Dec. 20, 1995, and U.S.Provisional Application No. 60/016,049, filed Apr. 22, 1996.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a cooling device for electrical orelectronic components, and to a method for manufacturing such a device.

BACKGROUND OF THE INVENTION

A cooling device of this type is already known (EP-A-0 483 058), havinghollow bodies as cooling ribs. Its manufacture is relatively complex.

Another type of cooling device is known from DE-PS 25 02 472. Here, therib-like cooling elements are made of aluminum plates, the ends of whichare each pressed into parallel slots in the base plate. The slot wallshave projections and indentations so that the cooling elements arefirmly fixed after being pressed into the slots. The manufacture of thiskind of heat sink is quite complex.

Furthermore, it is known from DE-PS 35 18 310 and EP-OS 0 483 058 thatindividual rib-like cooling elements can be fixed firmly in the baseplate by pressing the intermediate web between the slots in the baseplate against the wall of the cooling elements after the ends of thelatter have been inserted, thereby reducing the width of the slots. Itis recommended that the outer surfaces of the cooling elements, in theform either of plates or of hollow bodies, be given elevations andindentations so that the individual cooling elements can be better fixedin the base plate.

Moreover, it is known from DE-OS 41 06 437 to make cooling elements fromthin wires. The individual wires are bent into a meander such thatin-each case one and the same wire constitutes an integral part of alarge number of cooling elements; here a large number of such wires isarranged one behind the other in order to form rib-like structures. Thethin wires are connected to the base plate by means of a metal joint. Itis also known to blow a flow of coolant from above onto the rib-shapedstructure consisting of the plurality of cooling wires.

It is also known (EP-PS 0 123 795) that individual cooling elements ofcuboid cross-section can be made by obliquely cutting them out of ablock which is itself cuboid. an Milling grooves are provided in theblock from both face ends in such a way that the cross-section of thework piece's remaining material is given a meandering form. Here, too,manufacture is relatively complex.

Further, it is known from DE-GM 92 14 061 and 93 02 754 that the coolingelements can be amalgamated into one package by joining one end of eachof the cooling ribs to form a plate which, by means of a heat conductingpaste, for example, is in turn in contact with the base plate comprisingthe electronic components such as semi-conductor elements or thyristors.

Furthermore it is known from U.S. Pat. No. 1, 830,375 to fitribbon-shaped meanders to both outer surfaces of a flat hollow tube andto fix them by means of a wire spiral.

Finally, it is known from WO87/02443 that the base of the web portion ofU-shaped profiles can be welded onto a base plate in such way that thematerial of the profiles alloys itself to that of the base plate.

SUMMARY OF THE INVENTION

It is an object of the present invention to technically and functionallyimprove the cooling device of the class mentioned hereinabove and tosimplify its manufacture.

According to the present invention at least two cooling elements arecombined into a unitary package; this package consists of a ribbon ofgood heat-conducting material which has either been bent into ameandering or a serpentine shape so that adjacent windings each formrib-shaped cooling elements, or which has been formed into a U-shapedprofile so that several, or in particular at least four of saidU-profiles are arranged like segments of a comb next to and at adistance to one another on one side of the base plate. The distancebetween the profiles is far less than their expansion away from the baseplate, i.e. than their overall height.

In the embodiment where the two cooling ribs are combined into oneprofile segment of U-shaped cross-section, the base of the profilemember, i.e. the first web portion linking the two profile limbs, isfixed firmly in the respective longitudinal slot of the base plateresulting in surface contact with the inner walls of the longitudinalslot and good heat transmission.

For the manufacturing of the package of cooling elements, preference isgiven to using solder-coated ribbon-shaped sheet metal, on which thesolder--by means of which the package is connected to the baseplate--has already been plated in the form of a layer onto thesupporting layer of good thermal conductivity, i.e., the sheet metal.Particular preference is given to a coated aluminum alloy such as theAlMn or AlMnMg type. Plated aluminum alloys of this kind areparticularly suitable for sweating; they are made predominantly byrolling and, for the purposes of the present invention, are given theirmeander- or serpentine-shaped structure by bending, it being advisablethat the solder layer on the outer surfaces of those meander ends whichare to be joined to the base plate should be left bare.

In many cases, it suffices to put the package with its meander-shapedprofile against one side--where the meander ends are--of the base plateand to solder it on there. As far as the manufacturing is concerned thisis the least complicated method whilst still ensuring a good joint andsufficient heat transmission from the base plate to the meander-shapedpackage.

Instead of or complementary to the soldering joint, the meander-shapedribbon or the profiles can be pressed into the longitudinal slots in thebase plate by means of stretched pieces of wire, where they arepermanently deformed-and thus firmly fixed.

Heat transmission and fixing are improved yet further if the extrudedbase plate comprises longitudinal slots which are dovetailed incross-section. Pieces of wire are used to insert a portion of themeander-shaped ribbon or U-shaped profiles to the wider ends of thedovetailed longitudinal slots in order to facilitate the joining of themeander-shaped ribbon or the U-shaped profiles to the base plate bysqueezing or wedging and so that instead of just forming a goodmechanical joint, the heat transmission resistance is further reducedeven without soldering. In this manner, the cooling effect is furtherimproved and the "profiles" can be prevented from coming off bythemselves even if heated to a high temperature.

Other advantages and aspects of the invention will become apparent uponmaking reference to the specification, claims, and drawings to follow.

DESCRIPTION DRAWINGS

Embodiments of the present invention are described more detailed belowwith reference to the accompanying drawings in which:

FIG. 1 is a diagram of a cooling device according to the presentinvention;

FIG. 2 is a cross-sectional view of the cooling device of anotherembodiment according to the present invention;

FIG. 3 is a cross-sectional view of individual cooling elements made ofribbon folded into a meandering shape and combined into a unitarypackage;

FIG. 4 is a partial cross-sectional view of the ribbon used for makingthe cooling elements;

FIGS. 5-7 are other cross-sectional views of the cooling device;

FIG. 8 is a magnified partial cross-sectional view of the area whereeither the ribbon or the profile is fixed in a base plate slot; and,

FIG. 9 is a cross-sectional view of another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to embodiments illustrated.

According to FIG. 1, a series of electronic components 1a, 1b and 1c arefixed to a surface of the base plate 2 in such a way that the heatgenerated in the electronic components 1a, 1b and 1c is carried offeasily onto the base plate 2. The base plate 2 is made of aluminum, forexample, and it forms a profile segment together with the two sideplates 2b laterally supporting the ribbon 10 (see FIG. 4) made ofsolder-plated or commercially available aluminum sheet metal and foldedinto a meandering shape to form the package 3 (shown in FIG. 1). Thepackage 3 formed of the ribbon 10 is inserted into dovetailedlongitudinal slots 6 (shown in FIG. 8) and soldered onto the base plate2 with its meander ends 3c (also shown in FIG. 3), which in this exampleare bent into an approximately semicircular shape. A suitable solderingmaterial should be one which is quick to solder with, while at the sametime forms a mechanically firm joint and creates little heattransmission resistance between the base plate 2 and the package 3.

Representative dimensions of an embodiment according to the presentinvention as illustrated in FIGS. 2 and 3, are as follows:

a=60 mm

b=47 mm

e=48 mm

f=1 mm

g=2 mm

h=4 mm

i=approx. 30 mm

The electronic components 1a, 1b, 1c can also be arranged on the sideplates 2b of base plate 2.

According to FIG. 4, the supporting layer 3a of the metal ribbon 10 is0.9 mm thick and is coated on one side with a 0.1 mm thick layer ofsolder 3b made of special brazing filler metal, preferably AlSi.

According to FIGS. 2, 5, 6, 7 and 8, the meander-shaped ribbon 3 or theU-shaped profiles 13 are fixed in the longitudinal slots 6 of the baseplate 2 by means of straight, stretched pieces of wire 8 (illustrated inFIG. 8). The stretched pieces of wire 8 being clamped in betweenadjacent profile limbs 13 of the meander-shaped ribbons or profiles 13respectively by way of permanent deforming in such a way that themeander ends 3c (in the region of the "troughs") or the lower parts ofthe profile limbs 13a, 13b are slightly bent outwardly near the webportion 13c in the longitudinal slots 6 at an angle of e.g. 5°, so thatthey are in contact with the inner surfaces of the dovetailedlongitudinal slots 6.

According to FIGS. 2, 6 and 7, the pieces of wire 8 are clamped inbetween the profile limbs 13a, 13b at the bottom of the profiles 13having a U-shaped cross-section, i.e. on the web portion 13c, and fixedfirmly in the longitudinal slots 6.

It is better for the upper ends 2b1 of the side plate 2b or the sidelimbs to bend inwardly so as to form contact surfaces 2b2 for the ribbonor for the profile's 13 adjacent limb 13b.

Preferred measurements for the preferred embodiment of FIG. 7 are:

e=50.8 mm (height of profile)

f=1 mm (thickness of ribbon)

g=3.15 mm (distance between profiles)

h=5.1 mm (width of profile)

i=30 mm (width of package in the area of the cooling elements)

k=3.1 mm (profiles' internal width between the profile limbs)

A cooling element according to the package 3 of FIG. 7 is manufacturedas follows:

At first, the profile segment of the base plate 2, with its longitudinalslots 6 preferably being dovetailed in cross-section (FIG. 8), isextruded using aluminum. Then the bottom or end comprising the web 13cof the four U-shaped profiles 13 is inserted into the longitudinal slots6. Subsequently, pieces of wire 8, preferably with a squarecross-section, are inserted into the spaces between the profile limbs13a, 13b and are, ideally by means of a common tool such as a press,pushed down to the bottom, i.e. to the web portion 13c of the profiles13 thereby having to overcome a force or being squeezed and pressed sohard that the adjacent parts of the profile limbs 13a, 13b arepermanently deformed and lie flat and clamped against the side walls ofthe longitudinal slots 6.

The profiles 13 may be made not only of aluminum sheet metal asmentioned above: copper sheet metal or other materials of good heatconductivity are also well suited. Besides aluminum, copper is alsosuitable for the pieces of wire 8. Alloys of these with other materialsor alloys of other materials may also be used.

According to another embodiment of the invention as described in FIG. 9,the profiles 13 are hollow and form substantially rectangular inner andouter cross-sections. Instead of the sharply rectangular cross-sections(shown in FIG. 9), the hollow profiles 13 can also comprise rounded ends13c, 13d. Each hollow profile 13 extending longitudinally is inserted bythe lower ends 13c each into a respective longitudinal slot 6 while theupper closed ends 13d are free and form thermo-exchanging surfaces. Thelower ends 13c are connected to the base plate 2 by soldering. For thisreason, the outer surface of the hollow profiles 13 is covered with asolder layer as explained above so that by heating the lower ends 13cand the respective inner walls of the slots 6, a good mechanical and agood thermal connection between the hollow profiles 13 and the baseplate 2 are guaranteed.

Forming of the hollow profiles 13 is not very complicated. For instance,flat aluminum foils covered with a solder layer according to FIG. 4 arebent four times so that the side ends contact each other to allowsoldering longitudinally. Using high frequency welding is preferred inorder to form the tube-like hollow profiles 13. The ends opposite thesoldered ends can also be removed after soldering to form a profile 13similar to that found in FIG. 7.

While specific embodiments have been illustrated and described, numerousmodifications come to mind without significantly departing from thespirit of the invention and the scope of protection is only limited bythe scope of the accompanying claims.

We claim:
 1. A cooling device for electrical or electronic componentscomprising:a base plate to which the components to be cooled areconnected, the base plate having a longitudinal slot; a pair of rib-likecooling elements made of heat-conducting material, the pair of coolingelements being positioned substantially parallel to one another andbeing spaced by a predetermined distance, the cooling elements having afirst end and a second end, the pair of cooling elements having theirfirst ends positioned within the longitudinal slot, wherein the pair ofcooling elements are interconnected by a first web portion along attheir first ends to form a unit having a U-shaped profile incross-section, the first web portion being positioned within andconnected to the longitudinal slot of the base plate.
 2. A coolingdevice for electrical or electronic components comprising:a base plateto which the components to be cooled are connected, the base platehaving a longitudinal slot; a pair of rib-like cooling elements made ofheat-conducting material, the pair of cooling elements being positionedsubstantially parallel to one another and being spaced by apredetermined distance, the cooling elements having a first end and asecond end, the pair of cooling elements having their first endspositioned within the longitudinal slot, wherein the pair of coolingelements are interconnected by a first web portion along at their firstends to form a unit having a U-shaped profile in cross-section, thefirst web portion being positioned within and connected to thelongitudinal slot of the base plate, and the first ends of the coolingelements are soldered to the base plate.
 3. The cooling device of claim2, wherein the base plate was formed by means of extrusion.
 4. Thecooling device of claim 3, wherein the longitudinal slot of base plateis dovetailed in cross-section.
 5. The cooling device of claim 2,wherein the U-shaped profile is made of a composite material including asupporting layer made of heat conducting material and a plated solderlayer.
 6. The cooling device of claim 5, wherein the supporting layer ismade of an aluminum alloy and the solder layer is made of a brazingfiller metal.
 7. A cooling device for electrical or electroniccomponents comprising:a base plate to which the components to be cooledare connected, the base plate having a plurality of longitudinal slots,the slots being separated by a predetermined distance; a plurality ofpairs of rib-like cooling elements made of heat-conducting material andcorresponding to each longitudinal slot, the individual cooling elementsforming the pair being substantially parallel to one another, theindividual cooling elements each having a first end and a second end,each pair of cooling elements having their first ends placed withintheir corresponding longitudinal slot, wherein each pair of coolingelements are individually interconnected by a first web portion alongthe first ends of the cooling elements to form a unit having a pluralityof U-shaped profiles in cross-section which look like segments of acomb, the first web portion corresponding to each of the pairs ofcooling elements being positioned within and connected to itscorresponding longitudinal slot, and the first ends of each of thecooling elements are soldered to the base plate.
 8. The cooling deviceof claim 7, wherein the U-shaped profiles are made of a compositematerial including a supporting layer made of heat conducting materialand a plated solder layer.
 9. The cooling device of claim 8, wherein thesupporting layer is made of an aluminum alloy and the solder layer ismade of a brazing filler metal.
 10. A cooling device for electrical orelectronic components comprising:a base plate to which the components tobe cooled are connected, the base plate having a plurality oflongitudinal slots, the slots being separated by a predetermineddistance; a plurality of pairs of rib-like cooling elements made ofheat-conducting material and corresponding to each longitudinal slot,the individual cooling elements forming the pair being substantiallyparallel to one another, the individual cooling elements each having afirst end and a second end, each pair of cooling elements having theirfirst ends placed within their corresponding longitudinal slot, whereineach pair of cooling elements are individually interconnected by a firstweb portion along the first ends of the cooling elements, coolingelements in adjacent longitudinal slots being interconnected at theirsecond ends by second web portions to form a unit having a serpentineshaped cross section, the first web portion corresponding to each of thepairs of cooling elements being positioned within and connected to itscorresponding longitudinal slot, and the first ends of each of thecooling elements are soldered to the base plate.
 11. The cooling deviceof claim 10, wherein stretched pieces of wire are positioned over thefirst web portions of the pairs of cooling elements.
 12. The coolingdevice of claim 11, wherein the longitudinal slots have inside walls andthe pieces of wire force the first portions of the cooling elements tocontact the inside walls of their corresponding longitudinal slots. 13.The cooling device of claim 10, wherein the base plate was formed bymeans of extrusion.
 14. The cooling device of claim 13, wherein thelongitudinal slots of base plate is dovetailed in cross-section.
 15. Thecooling device of claim 10, wherein the serpentine shaped unit is madeof a composite material including a supporting layer made of heatconducting material and a plated solder layer.
 16. The cooling device ofclaim 15, wherein the supporting layer is made of an aluminum alloy andthe solder layer is made of a brazing filler metal.
 17. A cooling devicefor electrical or electronic components comprising:a base plate to whichthe components to be cooled are connected, the base plate having aplurality of longitudinal slots, the slots being separated by apredetermined distance; a plurality of pairs of rib-like coolingelements made of heat-conducting material and corresponding to eachlongitudinal slot, the individual cooling elements forming the pairbeing substantially parallel to one another, the individual coolingelements each having a first end and a second end, each pair of coolingelements having their first ends placed within their correspondinglongitudinal slot, wherein each pair of cooling elements areindividually interconnected by a first web portion along the first endsof the cooling elements and by a second web portion along their secondends to form a unit having a plurality of adjacent rectangularly-shapedprofiles in cross section, the first web portion corresponding to eachof the pairs of cooling elements being positioned within and connectedto its corresponding longitudinal slot, and the first ends of each ofthe cooling elements are soldered to the base plate.
 18. The coolingdevice of claim 17, wherein stretched pieces of wire are positioned overthe first web portions of the pairs of cooling elements.
 19. The coolingdevice of claim 18, wherein the longitudinal slots have inside walls andthe first portions of the cooling elements contact the inside walls oftheir corresponding longitudinal slots.
 20. The cooling device of claim17, wherein the base plate was formed by means of extrusion.
 21. Thecooling device of claim 20, wherein the longitudinal slots of base plateare dovetailed in cross-section.
 22. The cooling device of claim 17,wherein the unit is made of a composite material including a supportinglayer made of heat conducting material and a plated solder layer. 23.The cooling device of claim 22, wherein the supporting layer is made ofan aluminum alloy and the solder layer is made of a brazing fillermetal.